FS: Cooke 20-100, T3.1 with 9.5-47.5, T1.5 conversion and mattebox

[Markus Rave]

SOLD

Selling a rare Cooke Zoom 20-100mm, T3.1 including ARRI 6.6x6.6 mattebox, rod support and a conversion that gives you a 9.5-47.5 lens with an unbelieveable T1.5 for 16mm use. All lenses are free of any damage, no scratches or whatsoever. Coating is free of damage. Clean on the collimator, straight curve.

 

[Jeff Kieffer]

Bump for Markus.

He's a very serious seller, I bought a Peleng Fisheye Lens from him last year and I'm very happy with it. Perfect condition.

All the best for your sale.:thumbsup:

Nice lens BTW.

 

[David (dudi) Namir]

... a conversion that gives you a 9.5-47.5 lens with an unbelieveable T1.5 for 16mm use. All lenses ....

What kind of a conversion make the light twice as much? Also what do you mean "All lenses..." this is a one zoom deal, not many lenses.
Please explain.

 

[Markus Rave]

What kind of a conversion make the light twice as much? Also what do you mean "All lenses..." this is a one zoom deal, not many lenses.
Please explain.

Hi David,

Cooke offered this conversion and if you knew about 16mm Cooke lenses, you would know they had a T1.5 zoom 9.5-47.5mm in their range. It weighs as much as the 20-100. Anyway I am not a lens technician to explain why a T3.1 in 35mm comes down to a T1.5 in 16mm. Fact is it does.
In my not very technical understanding it must be the reduced negative area coupled with a much bigger lens diameter as needed for a T3.1 for 16mm use. Maybe someone more knowledgeable can enlighten us.

Of course the zoom has not only one lens but a couple of them inside. Fungus could be anywhere, especially scratches on the front and back element if you find this more clear. My lens has none of these.

Regards

 

[Markus Rave]

Bump for Markus.

He's a very serious seller, I bought a Peleng Fisheye Lens from him last year and I'm very happy with it. Perfect condition.

All the best for your sale.:thumbsup:

Nice lens BTW.

Thanks a lot for that, Jeff. Much appreciated.

 

[Noah Yuan-Vogel]

What kind of a conversion make the light twice as much?

It's not twice as much light, it is the same amount of light. The conversion is a focal length reducer, the opposite of a teleconverter/extender. When you shrink the image circle, the same quantity of light (minus very minor transmission loss for the extra optics) becomes more concentrated over the a smaller area. The contents of the image circle are exactly the same, only shrunken by 2x (2x less diameter, 4x less area, 4x/2stops "brighter"), to work the same way on 16mm as it did on 35mm, same DOF, etc. 20mm T3.1 for 35mm format will have the same DOF as 9.5mm T1.5 for 16mm format.

20mm / 9.5mm = 2.1 so it is using a 2.1x focal length reducer
T3.1 / 2.1 = T1.5 makes sense

 

[Tony Covell]

A Perfect explanation. I used to own 2 of these lenses for S16mm use on both NPR and Arri SR cameras. They were used for Dramas and Commercials for TV work. The images are stunning when they are set up and supported correctly. An excellent buy IMHO if you need a lens of this type. It should cover 2k 16:9 TV. on the S16mm optics.
Cheers Tonycovell.

 

[Markus Rave]

bump

 

[Markus Rave]

bump again

 

[Markus Rave]

bump

 

[Markus Rave]

Sale was pending. Lens FS again.

 

[Markus Rave]

still for sale